Adjectives, Case Endings, A few Questions, etc.
Please note: since I'm terrible at using the arabic keyboard I'm going to be romanizing Arabic words. Probably not well. So I apologize.
I was noticing that the sentence (or something like this) I am an American doctor doesn't have the ee ending for american but not for doctor but for the sentence I'm a Tunisian American both have the ee ending. Is that ee ending a noun-adjective agreement, a case ending something like that? And if so what is the rule that dictates that doctor not take that ending but demonyms do.
I think what you are talking about here is ياء النسبة (yá'ul Nisbah: Yá of relationship). This one is added to proper nouns to make adjectives out of them. Most commonly you will see it in country or geographical-related names (and hence the name). Many people in the Arab world used/still to have the last name (family name) in such format; Either relative to a country, some place, or even some craft (same thing in the Western culture I guess to some extent).
Thus, تونسي (túnisee), to be more accurate phonetically (túnisiy) means (Tunisian, someone from Tunisia) and أمريكي (amríkiy) means American or someone from America. You can find it in some crafts and jobs names as well, for example: ساعاتي (sá3átí) or (sá3atiy), meaning "Watchmaker" (from the word ساعات meaning "hours" as well as "watches").
As for "Doctor," well, this word is the same in Arabic (adapted from Latin or Western culture in general) so it is دكتور (doktúr) and originally it does not have any "ee" ending to it. It is a noun, and the "ee" ending is usually added to some noun to derive an adjective related to that noun (think of -(i)an in English, this is almost the equivalent of this "ee" in Arabic).